Up-to-date ISO build instructions?

I was looking for up-to-date build instructions for building my own pfSense 2.1 snapshot ISO to try more recent 'igb', 'mfi' driver from LSI since it supports a couple more of those pesky MegaRAID controllers.
The pfSense repository at github doesn't contain build instructions so far. (made me think of this) ;-)

Yep, usually the first fails because of some missed port dependencies (is documented as such) then you redo the build and from then on everything works quite fine.
The first build run usually takes quite long time to build all ports, so the more cores you throw at it, the faster it will go.